Anyone who has removed or replaced a rear bumper bar on a MK1, MK 2 , Daimler 250, Jaguar 240 and 340 series cars would be well aware of the problems of the 5/16 inch caged nut system used to secure the bumper bar to the mounting brackets. It is nearly a sheer impossibility to carry out this operation without the special caged nut which is a spring loaded boxed nut which sits in a slot in the bumper bar and to which the mounting brackets are bolted.
A club member in the country was in dire straits needing caged nuts to mount three rear bumper bars. He had tried every outlet to get these caged nuts but had been totally unsuccessful. It requires 8 of these nuts to mount a rear bumper
Back in 2001 I did some serious research into local sources and came up with a metric equivalent. It is an 8 mm caged nut and uses an 8X20 mm bolt to hold the bracket to the bumper. These nuts are readily available from Coventry Fasteners at 172 Lavarack Avenue, Eagle Farm [ph 3868 3655] for the grand price of 37 cents each and the 20 mm long by 8mm diameter bolts cost about 20 cents each. The Coventry part number is for the caged nuts is 26 8MCAGEN and the bolts are 26 8X20MZPBN
I contacted Coventry Fasteners and was advised that their computer showed negative stock. I have run across this problem before with this company and asked that they check the actual stock bins, Surprise! Surprise! They had over 100 in stock! A quick 10 minute trip from my workplace at Brisbane airport secured 30 for our country member and I grabbed an extra 10 for myself as every time you touch a rear bumper you can expect to write off some of the caged nuts due to corrosion.
Club members unable to get to a Coventry Fasteners branch can phone  3868 3655 ask for sales, pay by credit card and arrange delivery by whatever method desired such as by post or courier etc.